Hi Hakkers,
I came across some surprising behaviour with the LocalSnapshotStore - I was
trying to implement what I imagine would be a common pattern: remove older
snapshots each time a new snapshot is created. I did this with
`deleteSnapshots(SnapshotSelectionCriteria(meta.sequenceNr, meta.timestamp
- 1))`, only to find it would delete all snapshots for the given
persistence ID and sequenceNr, regardless of timestamp given.
After staring at my own code for a very long time, I looked at the source
for LocalSnapshotStore and found that it seems to ignore timestamps
altogether:
https://github.com/akka/akka/blob/master/akka-persistence/src/main/scala/akka/persistence/snapshot/local/LocalSnapshotStore.scala#L161
I initially thought this to be a bug, but looking at the history it appears
to have been intentionally removed:
https://github.com/akka/akka/commit/63baaf1b2b3d0fc6c1971307fd1e66d74106c968
I was able to fix this with a minor change in the attached diff. Is there
any interest in this fix? Or am I naive to some history around this?
I guess if it's the intended behaviour, I can easily enough subclass it and
override the relevant bits to take timestamps into account - does that
sound reasonable?
Thanks for Akka, it's amazing!
--
Stephen McDonald
http://jupo.org
--
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diff --git
a/akka-persistence/src/main/scala/akka/persistence/snapshot/local/LocalSnapshotStore.scala
b/akka-persistence/src/main/scala/akka/persistence/snapshot/local/LocalSnapshotStore.scala
index 4dc1ff6..b513816 100644
---
a/akka-persistence/src/main/scala/akka/persistence/snapshot/local/LocalSnapshotStore.scala
+++
b/akka-persistence/src/main/scala/akka/persistence/snapshot/local/LocalSnapshotStore.scala
@@ -25,6 +25,7 @@ import scala.util._
* Local filesystem backed snapshot store.
*/
private[persistence] class LocalSnapshotStore extends SnapshotStore with
ActorLogging {
+
private val FilenamePattern = """^snapshot-(.+)-(\d+)-(\d+)""".r
import akka.util.Helpers._
@@ -82,7 +83,7 @@ private[persistence] class LocalSnapshotStore extends
SnapshotStore with ActorLo
private def snapshotFiles(metadata: SnapshotMetadata): immutable.Seq[File] =
{
// pick all files for this persistenceId and sequenceNr, old journals
could have created multiple entries with appended timestamps
- snapshotDir.listFiles(new
SnapshotSeqNrFilenameFilter(metadata.persistenceId,
metadata.sequenceNr)).toVector
+ snapshotDir.listFiles(new
SnapshotSeqNrFilenameFilter(metadata.persistenceId, metadata.sequenceNr,
metadata.timestamp)).toVector
}
@scala.annotation.tailrec
@@ -156,13 +157,14 @@ private[persistence] class LocalSnapshotStore extends
SnapshotStore with ActorLo
}
}
- private final class SnapshotSeqNrFilenameFilter(persistenceId: String,
sequenceNr: Long) extends FilenameFilter {
- private final def matches(pid: String, snr: String): Boolean =
- pid.equals(URLEncoder.encode(persistenceId)) && Try(snr.toLong ==
sequenceNr).getOrElse(false)
+ private final class SnapshotSeqNrFilenameFilter(persistenceId: String,
sequenceNr: Long, timestamp: Long) extends FilenameFilter {
+ private final def matches(pid: String, snr: String, tms: String): Boolean
= {
+ pid.equals(URLEncoder.encode(persistenceId)) && Try(snr.toLong ==
sequenceNr).getOrElse(false) && Try(tms.toLong <= timestamp).getOrElse(false)
+ }
def accept(dir: File, name: String): Boolean =
name match {
- case FilenamePattern(pid, snr, tms) ⇒ matches(pid, snr)
+ case FilenamePattern(pid, snr, tms) ⇒ matches(pid, snr, tms)
case _ ⇒ false
}
